Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
  • Problem Description
• Data Files
• Parameters
• Instruments
• Project Information
• Funding

We quantified the metabolic responses of subtidal seaweed beds to varying thermal conditions during field trials conducted in June 2022, March 2024, October 2024, and January 2025. Using the Community In Situ Metabolism instrument (CISME), we measured dark respiration and gross photosynthesis rates of macroalgal patches in the rocky subtidal zone at approximately six meters depth in Tijeretas Bay, San Cristóbal Island. Measurements were conducted via SCUBA across a rocky platform covered with macroalgal beds. To isolate individual seaweed patches, we used a hose clamp adjusted to the same diameter (56 mm) as the CISME head, selecting 5 to 7 patches and clearing the surrounding seaweed. We then positioned the bottom surface of the CISME head over each target patch and secured it to the substrate using three adjustable retractor hooks. This setup enabled the soft foam ring at the base of the head to seal and isolate the patch within a closed chamber, where 88 mL of seawater recirculated between the chamber and the head during incubation. We ran the R+P program and quantified oxygen saturation under dark (respiration) and light (photosynthesis) conditions for each patch, measuring each process for 4 to 6 minutes.

To normalize rates to macroalgal biomass, we calculated the dry mass (g) of each patch by scraping and vacuuming samples into individual collection mesh bags. These were transported to the Marine Ecology Laboratory at the Galapagos Science Center, where they were weighed, dried at 60 °C for 24 hours, and weighed again.

The data were downloaded directly from the CISME's onboard computer. For each replicate, we obtained oxygen saturation and concentration values. We interpreted a decrease in oxygen saturation as respiration and an increase as photosynthesis. Each replicate has a matching biomass value of fleshy/filamentous seaweed. 

- Imported "Metabolism_CISME_data.csv" and "Dry weight_CISME_data.csv" into the BCO-DMO data system
- Added the dried weight of samples to the metabolic data by joining on year, month, and replicate and added the "dry_weight"
- Added parameter to indicate both month and year
- Added full date where applicable in "date" field
- Renamed parameters, replacing spaces with underscores
- Exported file as "969049_v1_cisme_galapagos.csv"

NSF Award Abstract:
Nearly all the animals that inhabit the ocean are "cold-blooded" or ectothermic, meaning their body temperatures match the temperature of the ocean around them. This has important consequences for their physiology and more broadly for the way marine ecosystems function. When ectotherms warm up, their metabolism increases; meaning they breathe more rapidly, and eat more just to stay alive. This is bad news for prey since a warm predator is a hungry predator. But warming also enables prey species to crawl or swim away more quickly when being hunted. Thus, everything speeds up in warm water. Energy flows more quickly from the sun to seaweeds (via photosynthesis), to the herbivores, then on up to the large predators at the top of the food chain. The research team is testing these ideas in the Galápagos Islands to determine how temperature influences marine ecosystems. Ongoing work in this iconic natural laboratory is helping marine ecologists understand the role of temperature and how this and other ecosystems could function in the future as climate change warms the ocean. Other broader impacts of the project include student training and on-site outreach to tourists and the local community about ocean warming and some of the lesser-known species that inhabit the Galápagos.

The broad goal of this project is to understand the effect that temperature has on patterns and processes in upwelling systems. Specifically, the team is measuring the temperature-dependence of herbivory and carnivory in rocky subtidal habitats of the Galápagos. They are performing field experiments to measure the relative and interactive effects of temperature, herbivory, and nutrient flux on the productivity and standing biomass of benthic macroalgae. Additionally, they are using in situ predation assays across spatial and temporal temperature gradients and mesocosm experiments to determine the relationship between ocean temperature and predation intensity for predator-prey pairings including whelk–barnacle, sea star–urchin, and fish–squid.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.